Chronic obstructive pulmonary disease is one of the commonest causes of morbidity and mortality in the world, and is increasing in prevalence. Current therapies are not very effective, and no current treatment prevents the relentless progression of airflow limitation that characterizes this disease. Smoking cessation is the only strategy that reduces this decline in lung function, and although bupropion is the most effective aid to quitting, more effective treatments of nicotine addiction are needed. The mainstay of treatment is bronchodilators for symptom relief, and inhaled anticholinergics and beta(2)-agonists are useful by reducing hyperinflation of the lungs. A new once-daily inhaled anticholinergic is the most effective bronchodilator, but long-acting inhaled beta(2)-agonists are also useful. Theophylline is used as an additional bronchodilator in more severe patients, and may have some anti-inflammatory action. In contrast, inhaled corticosteroids are poorly effective and do not reduce disease progression, although recent studies with combination inhalers (corticosteroid + long-acting beta(2)-agonist) have shown better effects. Long-term oxygen therapy is needed by patients with pulmonary hypertension and right heart failure. There is a pressing need to develop new classes of therapy, and several new drugs are current in development, including interleukin-8 antagonists, phosphodiesterase-4 inhibitors, protease inhibitors, and antioxidants.